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Global Economic Modeling using GTAP Future Directions
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Global Economic Modeling using GTAP Future Directions

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  1. Global Economic Modeling using GTAPFuture Directions presented to the Third Annual Conference in Global Economic Analysis, Melbourne by Thomas W. Hertel Center for Global Trade Analysis

  2. Outline • Demand parameter estimation: • import demand elasticities: maximum entropy • consumer demand: AIADS • Supply-side innovations: • industrial structure • productivity convergence • Policy modeling: TRQs • Dynamics

  3. Demand #1Estimating Armington Parameters • Most controversial parameters in GTAP: • “Structuralist” economists favor smaller values -- gives strong TOT effects, lower welfare gains • “Market oriented” economists favor larger ones -- gives larger gains from liberalization • Basically an empirical question • This study (led by Arndt and Liu) estimates trade parameters most consistent with historical experience.

  4. Methodology • Follows Arndt and Robinson work on Mozambique • Vary parameters and re-solve model to obtain best fit to historical data • Maximum Entropy criterion for evaluating how well the model tracks historical experience • Implemented using modified version of Rutherford’s GTAPinGAMS model • GTAP v4 database is starting point - shocks to factor endowments, govt cons, investment, and protection levels from 1995 to 1992, 1989, and 1986

  5. ME Estimates of D

  6. Future Directions • Provides ideal laboratory for testing alternative model specifications: • 2x rule relating D and M • CET between domestics and exports • In long run offers approach to model validation • Need for common historical data series

  7. Demand #2Modeling Consumer Behavior • Longer run projections hinge on demand specification • Income elasticities of demand change as individuals become wealthier • Econometric work always outdated – GTAP uses estimates from from 1980’s • Use Powell and Rimmer’s AIDADS demand system to track behavior over wide range and update elasticitiess

  8. Estimating AIDADS • Research with Cranfield, Eales and Preckel • 1985 International Comparisons Project • 64 countries ranging from Ethiopia to USA • 113 goods • MLE estimation

  9. Consumer budget shares vs. income

  10. AIDADS in GTAP • 9 good version incorporated AIDADS into GTAP (Wusheng Yu’s paper) • Introduce margins sectors to bridge difference: producer – consumer prices • Project to 2020: • demand at consumer prices • demand at producer prices • output requirements

  11. Estimated vs. Calibrated ElasticitiesThe Case for Newly Industrialized Economies

  12. Demand Side Experiment • Population and income growth • PE closure • no resource constraints • therefore pr. factor costs and prices fixed • Data • GTAP Baseline

  13. A focus on food: meat demand increases fastest for consumers

  14. Supply #1The Role of Industrial Structure in Morocco-EU FTA • Based on research conducted by Aziz Elbehri • Relationship with EU shapes Moroccan economy • access in agriculture restricted • privileged access in manufactures • FTA = free trade in industrial products by 2008 • primary impact on Moroccan manufactures • manufactures production highly concentrated • potential for rationalization – or wholesale collapse of manufactures

  15. Model Structure • Application of GTAP tech paper by Francois • Key assumptions: • Cournot competition among domestic producers who produce homogenous good • Domestic and foreign markets integrated • Foreign products differentiated • Domestic producers assume import prices fixed in calculating perceived demand elasticity • Data from industrial census

  16. Market structure and Model Calibration (Morocco; 1995) 4-plant Economies Concentration Herfindhal Price-cost of scale Ratio Index Markup (CDR) Meat products 66.43 0.2173 1.11 0.24 Vegetable oils & fat 87.27 0.4250 1.33 0.16 Dairy products 87.65 0.4254 1.49 0.13 Sugar 90.27 0.4893 2.39 0.11 Other food products 32.52 0.0790 1.06 0.10 Beverages & Tobacco 95.84 0.7907 2.45 0.10 Textiles 36.91 0.1214 1.07 0.19 Wearing apparel 25.67 0.0434 1.02 0.19 Wood products 81.48 0.3236 1.26 0.11 Paper & Publishing 51.72 0.2218 1.21 0.20 Chemical products 68.39 0.3892 1.35 0.16 Metal products 56.55 0.2315 1.19 0.09 Motor vehicles 86.56 0.2867 1.10 0.25 Light manufacturing 88.52 0.4138 1.21 0.15 Other manufacturing 93.25 0.5141 1.49 0.14 Source: Authors' calculations from annual manufacturing survey (Ministry of Commerce and Industry).

  17. Market Structure makes a differenceEU-Morocco FTA: IC/IRTS vs. PC/CRTS % change in output

  18. Supply #2Technology Convergence • Controversy over China’s future trade position for meat products • everyone predicts rapid growth in demand • but less work on the supply-side • China’s livestock productivity still far below intn’l frontier – but catching up is occurring • What are implications for trade? • Based on research led by Alejandro Nin

  19. Cumulative Productivity Growth Rates for China (PFP) Pigs Poultry

  20. Productivity Forecasts for China Using the Logistic Functional Form Pigs Poultry

  21. Bootstrapped Distribution of Productivity Forecasts

  22. Uncertainty in ProductivityImpact on Projected Trade Balances 95% confidence intervals

  23. Recent Developments in PolicyModeling TRQs • Introduced in UR as way of ensuring minimum access in presence of very high tariffs • Makes analysis of partial liberalization vastly more complex • Who gets rents initially? What happens to these rents when enlarge quota or cut tariffs? • Based on: • GTAP technical paper by Elbehri and Pearson • sugar application led by Aziz Elbehri

  24. TRQ generates economic rents Price Pw(1 + T2) Rents Net Import Demand Pw(1 + T1) Tariff Revenues Pw Q* Q Imports

  25. EU TARIFF CUTLost Quota Rents Drive Exporters’ Welfare

  26. EU EU Quota Expansion Higher Rents Raise Exporters’ Welfare

  27. EU Tariff Cut & Quota ExpansionWelfare Gains for BOTH EU and Exporters

  28. Recent Developments Modeling Dynamics • Dynamic GTAP model developed by Ianchovichina and McDougall • Builds on standard GTAP Model • Recursive Dynamic with accumulation of Capital stocks and wealth • Foreign Capital ownership. • Disequilibrium theory of Investment.

  29. Foreign Capital Ownership • Households invest either domestically or overseas via a global trust (no bilateral detail on ownership) • Shares of savings held in foreign and domestic assets are held constant, subject to adding-up constraints

  30. Disequilibrium Approach • Problem #1: Equalization of rates of return poses a problem implies perfect capital mobility. This is clearly not the case. • Problem #2: Theory and data are inconsistent: high investment in some regions with low ROR • Solution #1: Gradual equalization of rates of return with perfect capital mobility in long-run only • Solution #2: Introduce errors in expectations

  31. Analysis of China’s WTO Accession • Research by Terrie Walmsley • Baseline from1995 to 2020 (13 periods) • Shocks to labor force and population • Endogenous capital accumulation • TFP calibrated to hit GDP targets • UR agreement 1995-2005 • China’s pre-WTO accession tariff cuts 1995 to 2000

  32. China’s Real GDP and Utility cumulative % difference from base

  33. Impact of China’s accession on employment NAM Apparel Index: 1995 = 100

  34. Alternative path for China’s quota abolition % subject to free trade

  35. Impact of 10 year phase-out on Employment in NAM Apparel Index: 1995 = 100

  36. SummaryForecast Demise of the Generic GTAP Application • In future, applications will be tailored much more closely to the economy/policy at hand • GTAP data base, technical papers and software provide starting point • Researchers must supplement this with: • econometric work on parameters or shocks • additional detail on structure of the economy • careful analysis and modeling of policies